1. Field of the Invention
The present invention relates to a storage case for a diffraction grating, used for transportation, storage, and the like of a diffraction grating which is an optical element.
2. Related Background Art
A diffraction grating has been employed as one of optical elements in a light pickup optical system in an apparatus for reproducing a CD, CD-ROM, or DVD, and the like. The diffraction grating diffracts light emitted from a laser diode or the like and splits it into a plurality of rays. The surface of the diffraction grating is formed with minute irregularities which diffract the light transmitted through the diffraction grating. The laser rays split by the diffraction grating irradiate a disc such as CD, thus forming a main beam and a pair of side beams. For reading out information of the disc, the main beam and side beams must be irradiated in a predetermined positional relationship. In order for the main beam and side beams to be irradiated in such a manner, it is necessary for the diffraction grating to be installed in the light pickup optical system with its irregularities oriented in a predetermined direction.
Meanwhile, after being manufactured, a number of diffraction gratings are shipped as being accommodated together in a storage package. Then, at their receiving end, the diffraction gratings are individually taken out from the storage package and are assembled into light pickup optical systems. As such a storage package, the one shown in FIG. 6 has been known, for example. This storage package A is formed by blowing or the like and is provided with a number of recesses B for receiving diffraction gratings C. As the diffraction gratings C are accommodated in the recesses B one by one, the number of diffraction gratings can be accommodated in the storage package A.